CSF neurofilament light chain testing as an aid to determine treatment strategies in MS

Abstract

Objective: To evaluate the use of CSF neurofilament light chain (NfL) measurements in clinical practice as well as their effect on treatment strategies and outcomes in multiple sclerosis (MS) patients. Methods: This was an observational cohort study of MS patients who had a CSF NfL measurement between December 2015 and July 2018 as part of their routine clinical care. Treatment strategies were classified as ‘No Treatment/No Escalation’ (no treatment or no escalation of treatment) or ‘Treatment/Escalation’ (first-line injectable/oral disease-modifying therapies, highly-active disease-modifying therapies or treatment escalation). Change in expanded disability status scale (EDSS) scores was evaluated after 1-year follow-up. Results: Of 203 MS patients, 117 (58%) had relapsing-remitting MS (RRMS). Disease activity was most frequently indicated by elevated CSF NfL (n=85), followed by clinical (n=81) and MRI activity (n=65). CSF NfL measurements were independently associated with clinical (P=0.02) and MRI activity (P<0.001). Of those with elevated CSF NfL as the only evidence of disease activity (n=22), 77% had progressive MS (PMS). In PMS patients, 17 (20%) had elevated CSF NfL as the sole indicator of disease activity. Elevated CSF NfL resulted more frequently in ‘Treatment/Escalation’ than normal CSF NfL (P<0.001). Median EDSS change at follow-up was similar between patients receiving ‘No Treatment/No Escalation’ and ‘Treatment/Escalation’ decisions (P=0.81). Conclusions: CSF NfL measurements informed treatment strategies, alongside clinical and MRI measures. CSF NfL levels was the only indicator of disease activity in a subset of patients, which was more pronounced in PMS patients. Elevated CSF NfL was associated with more ‘Treatment/Escalation’ strategies, which had an impact on EDSS outcomes at 1 year.